Astronauts wear special device on the ear why give reason

Valsalva device

Explanation: Valsalva device allows astronauts to equalize the pressure in their ears by performing the Valsalva maneuver inside the suit without using their hands to block their nose.

Astronauts wear communication devices called intercoms on the ear.

Explanation:

We know that the outer space is a vacuum environment and hence sound waves cannot travel through space. Hence an alternative means of communication is necessary for proper communication between two astronauts. This alternative is the use of intercom. Its functioning is similar to a walkie-talkie, it transmits and recieves radio waves for communication

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.

k2s for potassium sulphide